Flat multifilament yarn knitted fabric

ABSTRACT

A flat multifilament yarn knitted fabric having excellent bulkiness, drape, and water•sweat-absorbability is a knitted fabric comprising multifilament yarns each comprising a plurality of flat cross section shape-having filaments comprising a fiber-forming thermoplastic polymer as a main component. In the above-described flat cross section, three or more expanded portions expanded toward the outside of the longitudinal central line of the flat cross section per half side of the flat cross section, and two or more constricted portions formed between the expanded portions per half side are approximately symmetrically formed on both the sides of the longitudinal central line with respect to the above-described longitudinal central line. Cross section flatness represented by the ratio (B/C 1 ) of the length (B) of the above-described modified cross section in the direction of the longitudinal central line to the maximum width (C 1 ) in the direction orthogonal to the direction of the longitudinal central line is in a range of 2 to 6. The above-described multifilament yarns are comprised in the knitted fabric in an amount of 50 to 100 percent by weight based on the total weight of the knitted fabric.

TECHNICAL FIELD

The present invention relates to a flat multifilament yarn knittedfabric. In more detail, the present invention relates to a knittedfabric which comprises multifilament yarns comprising flat and two ormore constricted portion-having filaments and has bulkiness, excellentdrape and high water absorbability.

BACKGROUND ART

Hitherto, many knitted fabrics have been proposed in the fields of innerwears represented by underwear, sports wears, and the like. Since theknitted fabrics for the inner wears among them are directly brought intocontact with the skins, excellent drape, bulkiness and waterabsorbability are required.

On the other hand, fibers comprising a fiber-forming thermoplasticpolymer such as a polyester or a polyamide have been used in a widerange from clothing uses to industrial uses due to the excellentcharacteristics of the fibers. Polyester fibers among the fibers havewidely been used as yarns constituting woven fabrics, because of havingmany excellent characteristics such as excellent fiber strengths,dimensional stability and easy care property.

However, there has been a problem that the drape of a knitted fabric hasbeen deteriorated, when yarns comprising a fiber-forming thermoplasticpolymer are subjected to a false-twisting and crimping treatment andthen knitted into the knitted fabric to enhance its bulkiness.

Such the drape and the bulkiness are generally the mutually conflictingproperties. For example, there has been a problem that the bulkiness ofa knitted fabric has been deteriorated, when the knitted fabric issubjected to an alkali reduction treatment to enhance the drape of theknitted fabric or when twisted yarns are knitted into the knitted fabricto enhance its drape.

Additionally, the water absorbability of a knitted fabric formed fromyarns comprising a fiber-forming thermoplastic polymer is usuallyinsufficient. The improvement of the water absorbability has thereforebeen required.

As a knitted fabric having the water absorbability and the drape, aknitted fabric comprising multifilament yarns each comprising aplurality of flat W-shaped cross section shape-having filaments has beenproposed in JP-A 11-222721 (hereinafter, JP-A means “Japanese UnexaminedPatent Publication”).

However, such the knitted fabric comprising the multifilament yarns eachcomprising a plurality of the flat W-shaped cross section shape-havingfilaments has excellent water absorbability, but is still insufficientat the point of the drape.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a knitted fabrichaving bulkiness, excellent drape and high water absorbability. Theabove-described object can be achieved with the flat multifilament yarnknitted fabric of the present invention.

The flat multifilament yarn knitted fabric of the present invention is aknitted fabric comprising multifilament yarns each comprising aplurality of flat cross section shape-having filaments comprising afiber-forming thermoplastic polymer as a main component, characterizedin that

three or more expanded portions expanded toward the outside of thelongitudinal central line of the flat cross section of theabove-described filament per half side of the flat cross section and twoor more constricted portions formed between the expanded portions perhalf side are formed on both the sides of the longitudinal central line,approximately symmetrically with respect to the above-describedlongitudinal central line, in the flat cross section of the filament;

cross section flatness represented by the ratio (B/C1) of the length (B)of the above-described modified cross section in the direction of thelongitudinal central line to the maximum width (C1) in the directionorthogonal to the direction of the longitudinal central line is in arange of 2 to 6; and

the above-described multifilament yarns are comprised in the knittedfabric in an amount of 50 to 100 percent by weight based on the totalweight of the knitted fabric.

Therein, the above-described fiber-forming thermoplastic polymer ispreferably selected from polyesters, polyamides, polyvinylidenechloride, and polypropylene.

Further, in the flat cross section of the above-described filament, itis preferable that the ratio (C1/C2) of the maximum width (C1) to theminimum width (C2) is 1.05 to 4.00.

It is preferable that the above-described multifilament yarns contains amatting agent in an amount of not less than 0.2 percent by weight,because more excellent drape is obtained. The total fineness of such themultifilament yarn is preferably 20 to 170 dtex, and the fineness of thesingle filament is preferably 0.5 to 5 dtex.

In the flat multifilament yarn knitted fabric of the present invention,it is preferable that the knit construction is a knit constructionselected from ponti roma, Milano rib, tuck rib, back seed stitch (backKanoko), single pique, double pique, half, satin, back half, queenscord, shark skin, double raschel, and double tricot.

In the flat multifilament yarn knitted fabric of the present invention,it is preferable that a K value determined by the following expressionis not more than 35×10³, as the whole of the knitted fabric. When suchthe K value is more than 35×10³, the bulkiness is liable to isdeteriorated.K=Co×We×(D/1.1)^(1/2)wherein Co is the courses (courses/2.54 cm) of the knitted fabric; We isthe wales (wales/2.54 cm) of the knitted fabric; D is the average value(dtex) of the total finenesses of the yarn constituting the knittedfabric.

In the flat multifilament yarn knitted fabric of the invention, it ispreferable that the bulkiness of the knitted fabric, measured by JIS L1018-1998, 6. 20, is not less than 2.1 cm³/g. Further, it is preferablethat the flexural rigidity of the knitted fabric, measured by a KEShand-measuring system, is not more than 0.02 cN·cm²/cm. Furthermore, itis preferable that the water-absorbing speed of the knitted fabric,measured by JIS L 1096-1998, 6. 26, 1(2) B method (Byreck method), isnot less than 30 mm.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory drawing showing an example of the cross sectionshape of each of the filaments constituting the flat multifilament yarnscomprised in the flat multifilament yarn knitted fabric of the presentinvention.

FIG. 2 is an explanatory drawing showing the other example of the crosssection shape of each of the filaments constituting the flatmultifilament yarns comprised in the flat multifilament yarn knittedfabric of the present invention.

FIG. 3 is an explanatory drawing showing the further other example ofthe cross section shape of each of the filaments constituting the flatmultifilament yarns comprised in the flat multifilament yarn knittedfabric of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The inventors of the present invention have found the following. In aknitted fabric comprising multifilament yarns each comprising aplurality of flat cross section shape-having filaments comprising afiber-forming thermoplastic polymer as a main component, wherein threeor more, preferably four or more, further preferably four to six,expanded portions expanded toward the outside of the longitudinalcentral line of the flat cross section of the above-described filamentper half side of the flat cross section and two or more, preferablythree or more, further preferably three to five, constricted portionsformed between the expanded portions per half side are formed on boththe sides of the longitudinal central line, approximately symmetricallywith respect to the above-described longitudinal central line, in theflat cross section of the filament, and further wherein cross sectionflatness represented by the ratio (B/C1) of the length (B) of theabove-described modified cross section in the direction of thelongitudinal central line to the maximum width (C1) in the directionorthogonal to the direction of the longitudinal central line iscontrolled within a range of 2 to 6, excellent bulkiness is obtained,because the flat multifilament yarns are tightly brought into contactwith each other on their flat surfaces at the connection points of theknitted fabric construction due to the contact pressure of theconstruction and simultaneously slipped and spread to form the loops ofthe knitted fabric, and high flexibility at the connection points of theknitted fabric construction and excellent drape are also obtained,because the surfaces of the mutually overlapped flat filaments areroughed with the expanded portions and the constricted portions toreduce frictional resistance between the filaments.

Further, the inventors of the present invention have found that theconstricted portions formed on the flat surfaces of the flatmultifilament yarns develop capillary phenomena for liquids, whereby theknitted fabric of the present invention exhibits excellent waterabsorbability and excellent sweat absorbability for water and sweat,respectively.

The present invention has been completed on the basis of theabove-described findings.

The flat multifilament yarn knitted fabric of the present invention isthe knitted fabric comprising the multifilament yarns each comprising aplurality of the flat cross section shape-having filaments comprisingthe fiber-forming thermoplastic polymer as the main component.

In the above-described multifilament yarn, the cross section shape ofthe single filament is a shape in which the width in the directionvertical to the longitudinal central line is relatively shorter than thelength of the central line, namely a flat shape, for example, as shownin FIG. 1.

In the cross section 1 shown in FIG. 1, three or more (four in theFIG. 1) expanded portions 3 expanded toward the outside of thelongitudinal central line 2 per half side of the cross section and twoor more (three in FIG. 1) constricted portions formed between theexpanded portions 3 per half side are formed on both the sides of thelongitudinal central line, symmetrically with respect to thelongitudinal central line.

Herein, the expanded portions formed on one side are approximatelysymmetrically placed to the expanded portions formed on the other sidewith respect to the longitudinal central line, and the constrictedportions formed on one side are also approximately symmetrically placedto the constricted portions formed on the other side with respect to thelongitudinal central line. But it is not necessary that the shapes ofthe expanded portions and the constricted portions formed on both thesides are perfectly symmetrical.

In the cross section of FIG. 1, the cross section flatness representedby the ratio (B/C1) of the maximum length (B) in the longitudinaldirection to the maximum width (C1) in the direction orthogonal to thelongitudinal direction is in a range of 2 to 6.

In the cross section of the single filament in the above-described flatmultifilament yarn, the number of the expanded portions is three ormore, preferably four or more, further preferably four to six, per oneside, as described above. The number of the constricted portions is alsotwo or more, preferably three or more, further preferably three to five,per one side, as described above. Additionally, the cross sectionflatness is 2 to 6, preferably 3 to 5, as described above.

When the number of the expanded portions is two or less, thereby, whenthe number of the constricted portion is one or less per one side,frictional resistance on the peripheral surface of the filament isenlarged, and the spreading of the knitted fabric construction due tothe pressure contact at the connection points is insufficient. Thewater•sweat absorbability of the obtained knitted fabric is alsoinsufficient, because the constricted portions on the peripheral surfaceof the filament are reduced.

In the flat multifilament yarn knitted fabric of the present invention,the cross section flatness (B/C1) in the cross section of the singlefilament in the flat multifilament yarn is 2 to 6, preferably 3 to 5, asdescribed above. When the cross section flatness is less than 2, theflexural rigidity of the filament is enhanced, and the desired drape istherefore not obtained. Further, when the cross section flatness is lessthan 2, the spreading of the multifilament yarns due to the pressurecontact in the knitted fabric, especially at the connection points ofthe knitted fabric construction, is insufficient, and the desired drapeis therefore not obtained.

In the cross section shape of the single filament in the flatmultifilament yarn used in the knitted fabric of the present invention,the ratio (C1/C2) of the maximum width (C1) in the direction orthogonalto the longitudinal central line to the minimum value (C2) is preferably1.05 to 4.00, more preferably 1.10 to 2.50. The above-described ratio(C1/C2) is a parameter related to the depth of the constricted portionof the single flat filament. When the ratio (C1/C2) is less than 1.05,namely when the depth of the constricted portion is small, frictionalresistance between the filaments is enlarged. Thereby, flexibility atthe connection points of the knitted fabric construction is oftendeteriorated, and the drape of the knitted fabric is therefore ofteninsufficient. Further, the water•sweat absorbability of the knittedfabric is often insufficient. When the ratio (C1/C2) exceeds 4.0, thedepth of the constricted portion is excessively enlarged, and the actioneffect is saturated. Furthermore, troubles such as the unstableness offiber productivity, the development of cracks in the constrictedportion, and the deterioration in the uniformity of the filament crosssection are often caused.

The other examples of the cross section shape of the single filament inthe flat multifilament yarn used in the flat multifilament yarn woven ofthe present invention are shown in FIGS. 2 and 3, respectively.

The cross section of the filament 1 shown in FIG. 2 has the same shapeas the cross section shape described in FIG. 1 on both the sides of thelongitudinal central line 2, but the cross section shape of the expandedportion 3 is gentle like an arc along the major axis of an ellipse.Thereby, the depth of the constricted portion 4 is small.

The cross section of the filament 1 shown in FIG. 3 has four expandedportions and three constricted portions per one side on both the sidesof the longitudinal central line, but the width and height of oneexpanded portion 3 a are smaller than those of the other expandedportions. Thereby, the depths of the valley bottoms of the constrictedportions 4 a on both the sides from the tips of the expanded portion 3 aare smaller than those of the other constricted portion 4.

Next, the filaments constituting the multifilament yarns comprise thefiber-forming thermoplastic polymer. Said fiber-forming thermoplasticpolymer is especially not limited, and includes polyesters representedby polyethylene terephthalate and polytrimethylene terephthalate,polyamides, polyvinylidene chloride, polypropylene, and their copolymerscopolymerized with the third components. Among them, the polyesters arepreferably exemplified, because of being easily produced.

And, it is preferable on the acquisition of more excellent drape thatsaid fiber-forming thermoplastic polymer contains a matting agent in anamount of not less than 0.2 percent by weight (more preferably 1.0 to3.5 percent by weight, especially preferably 1.5 to 2.8 percent byweight). Such the matting agent includes known inorganic fine particlessuch as titanium dioxide.

Except the matting agent, the above-described fiber-formingthermoplastic polymer may, if necessary, furthermore contain one or moreadditives selected from fine pore-forming agents (for example, metalorganic sulfonates), cation dye-dyeable agents (for example, isophthalicacid sulfonium salts), antioxidizing agents (for example, hinderedphenol-based antioxidizing agents), heat stabilizers, flame retardants(for example, antimony trioxide), fluorescent brightening agents,colorants, antistatic agents (for example, metal sulfonates), moistureabsorbents (for example, polyoxyalkylene glycols), and the like.

The total fineness of said multifilament yarn and the fineness of saidsingle filament are especially not limited, but it is preferable on theacquisition of bulkiness, excellent drape and high water absorbabilitythat the total fineness of the multifilament yarn and the fineness ofthe single filament are 20 to 170 dtex (more preferably 30 to 100 dtex)and 0.5 to 5 dtex (more preferably 1 to 4 dtex), respectively.

In the flat multifilament yarn used the flat multifilament yarn knittedfabric of the present invention, the twist rate of the yarn isespecially not limited, can suitably be set, but is generally preferably0 to 2,500 T/m, more preferably 0 to 600 T/m, especially preferably 0T/m (untwisted), on the acquisition of excellent drape.

The multifilament yarn used in the present invention may be subjected toa twisting treatment such as a false twisting treatment or to an airtreatment such as Taslan treatment or an interlacing treatment, so longas the objective knitted fabric of the present invention is obtained.

It is necessary that such the multifilament yarns are contained in anamount of 50 to 100 percent by weight, preferably 60 to 100 percent byweight, especially preferably 100 percent by weight, based on the totalamount of the knitted fabric. The smaller content of said multifilamentyarns than 50 percent by weight is not preferable, because sufficientbulkiness, drape and sweat absorbability are not obtained. When thecontent of the multifilament yarns is not less than 50 percent byweight, the flat multifilament yarn knitted fabric of the presentinvention may be interknitted with a different kind of yarns. Theabove-described different kind of yarns include monofilament yarns,multifilament yarns and spun yarns, and may have one or more specialfunctions such as an antistatic function and a brightening function.Further, the flat multifilament yarns may singly constitute the knittedfabric or constitute the knitted fabric together with a different kindof yarns in the form of composite yarns such as twisted yarns or airblended yarns.

In the flat multifilament yarn knitted fabric of the present invention,the density of the knitted fabric is especially not limited, but theranges of 40 to 80 courses/2.54 cm (more preferably 50 to 70 courses/254 cm) and 30 to 70 wales/2.54 cm (more preferably 40 to 65 wales/2.54cm) are suitable for satisfying both the performances of drape andbulkiness.

Especially, it is preferable that a coefficient K determined by thefollowing expression is not more than 35×10³ (preferably 17×10³ to30×10³, especially preferably 20×10³ to 28×10³).K=Co×We×(D/1.1)^(1/2)

wherein Co is the courses (courses/2.54 cm) of the knitted fabric; We isthe wales (wales/2.54 cm) of the knitted fabric; D is the average value(dtex) of the total finenesses of the yarn constituting the knittedfabric.

When the above-described K value is larger than 35×10³, the K value isnot preferable, because sufficient bulkiness is not obtained. When saidK value is conversely less than 17×10³, sweat absorption may bedeteriorated.

In the flat multifilament yarn knitted fabric of the present invention,the knit construction is especially not limited, and a known knitconstruction such as a warp knit construction or a circular knitconstruction can be used. For example, circular knitted fabrics such asponti roma, Milano rib, tuck rib, back seed stitch (back Kanoko), singlepique and double pique, single warp knitted fabrics such as half, satin,back half, queens cord and shark skin, and double warp knitted fabricssuch as double raschel, and double tricot are cited.

The flat multifilament yarn knitted fabric of the present invention canbe produced, for example, by spinning with a spinneret having such theshape nozzles as shown in FIG. 2C at page 5 in JP-A 56-107044 to obtainthe flat multifilament yarn, if necessary, combining the obtained flatmultifilament yarn with a different kind of yarn to form the compositeyarn, and then knitting the composite yarn by an ordinary knittingmethod. The knitted fabric of the present invention can be dyed andfinished by ordinary methods. When the flat multifilament yarn is apolyester yarn, an alkali reduction treatment can be applied to saidknitted fabric. In the finishing treatment, one or more of a waterabsorbability-promoting treatment (for example, a treatment for coatingor impregnating a water-absorbing agent such as an anionic hydrophilicpolymer), a water-repelling treatment (for example, a treatment forcoating or impregnating a water-repelling agent such as a fluorinatedcompound), an ultraviolet light-screening treatment (for example, atreatment for coating or impregnating a finely particulate metal oxide),an antistatic treatment, a deodorizer-imparting treatment, amothproofing agent-imparting treatment, and a luminous agent treatmentmay simultaneously or sequentially be applied.

In the flat multifilament yarn knitted fabric of the present invention,bulkiness measured according to JIS L 1018-1998, 6. 20 is preferably notless than 2.1 cm³/g, especially preferably 2.2 to 3.0 cm³/g.

Further, in the flat multifilament yarn knitted fabric of the presentinvention, flexural rigidity measured with a KES hand-measuring systemas drape is preferably not more than 0.02 cN·cm²/cm, especiallypreferably 0.010 to 0.018 cN·cm²/cm.

Furthermore, in the flat multifilament yarn knitted fabric of thepresent invention, water-absorbing speed measured by JIS L 1018-1998, 6.26, 1(2) B method (Byreck method) is preferably not less than 30 mm,especially preferably 50 to 70 mm.

In the flat multifilament yarn woven fabric of the present invention,excellent bulkiness is obtained, because the flat multifilament yarnsconstituting the knitted fabric are slipped on the mutual contactsurfaces of the mutually contacting single filaments with contactpressures at the connection points of the knitted fabric construction,flattened, and simultaneously spread in the lateral direction to formthe loops of the knitted fabric.

Further, in the flat multifilament yarn woven fabric of the presentinvention, the knitted fabric exhibiting lowered bending resistance,improved flexibility and excellent drape is obtained by theabove-described flattening of the yarns. Additionally, the peripheralsurface of the single filament in the flat multifilament yarn isroughened with three or more expanded portions per one side and with twoor more constricted portions formed therebetween. Even when the singlefilaments contact with each other or even when the single filaments arebrought into press contact with each other at the connection points ofthe knitted fabric construction, the contact area between the singlefilaments is small. Thereby, the surface frictional resistance isreduced to contribute to the improvement in the drape of the knittedfabric. Further, even when the single filaments contact with each other,the constricted portions on the peripheral surfaces of the singlefilaments are not or slightly closed. Therefore, water or sweat iseasily diffused by the capillary phenomena of the constricted portions,and the obtained knitted fabric exhibits excellent water absorbabilityand sweat absorb ability.

The flat multifilament yarn knitted fabric of the present invention issuitably used as a material for various clothes, for example, for innerwears such as underwear and sports wears, because of having the highbulkiness, excellent drape, and high water•sweat absorbability.

EXAMPLES

The present invention will be explained in more detail hereafter withthe following examples, but the present invention is not limited to theexamples. Therein, measurement items in Examples were measured by thefollowing methods, respectively.

(1). Water Absorbability

The water absorbability was measured by JIS L 1096-1998, 6. 26, 1(2) Bmethod with the number n of 5, and the average value was calculated.

(2). Bulkiness

The bulkiness was measured by JIS L 1018-1998, 6. 20 with the number nof 5, and the average value was calculated.

(3). Flexural Rigidity

The flexural rigidity was measured with KES (Kawabata Evaluation System)hand-measuring system (type KESFB2, manufactured by Kato Tech Co.) withthe number n of 5, and the average value was calculated.

(4). Hand

The hand was classified into the following five grades with hand touchand evaluated.

5 grade: extremely high flexibility, extremely excellent hand.

4 grade: high flexibility, excellent hand.

3 grade: good flexibility, good hand.

2 grade: slightly insufficient flexibility, slightly dissatisfactoryhand.

1 grade: bad flexibility, bad hand.

(5). Over-all Evaluation

The over-all evaluation was classified into the following four grades.

4 grade: extremely excellent.

3 grade: excellent.

2 grade: slightly dissatisfactory.

1 grade: bad.

Example 1

Polyethylene terephthalate resin containing titanium dioxide in anamount of 2.5 percent by weight as a matting agent was extruded at aspinning temperature of 300° C. through thirty melt-spinning holes (eachhole has four circular expanded portions and three constricted portionsformed between the expanded portions per one side on both the sides ofthe longitudinal central line) opened in a spinneret and each having ashape corresponding to the filament cross section shape shown in FIG. 1.The extruded filament-like melted polymer flows are cooled andsolidified and simultaneously taken off at a take-off speed of 4,000m/min. The obtained undrawn multifilaments were not wound up andimmediately drawn at a draw ratio of 1.3 at a temperature of 97° C. toproduce the drawn multifilament yarn having a yarn count of 84 dtex/30filaments. This drawn multifilament yarn comprised the filaments eachhaving the cross section shape shown in FIG. 1. The cross sectionflatness of the cross section shape of each filament was 3.2, and aratio C1/C2 value in the cross section width of the filament was 1.2.

Subsequently, said flat multifilament yarns thus produced were fed intoa front reed and a back reed in an untwisted state, and then knitted byan ordinary knitting method (tricot knitting machine, 28G) to obtain theknitted fabric containing 100% of the above-described flat multifilamentyarns and having a half knit construction (back: 12/10, front: 10/23).The knitted fabric was subjected to ordinary dyeing and finishingtreatments. The finished knitted fabric had a knit density (62courses/2.54 cm, 50 wales/2.54 cm, K value 26.84×10³).

In said knitted fabric, sweat absorbability: 56 mm, bulkiness: 2.27cm³/g, flexural rigidity: 0.017 cN·cm²/cm, hand: 5 grade, over-allevaluation: 4 grade.

Example 2

A flat multifilament yarn knitted fabric was obtained similarly toExample 1, except that the knit density was changed into a knit density(70 courses/2.54 cm, 50 wales/2.54 cm, K value 30×10³), while using thesame yarns.

In said knitted fabric, sweat absorbability: 57 mm, bulkiness: 2.20cm³/g, flexural rigidity: 0.018 cN·cm²/cm, hand: 4 grade, over-allevaluation: 3 grade.

Example 3

A flat multifilament yarn knitted fabric was obtained similarly toExample 1, except that the content of the titanium dioxide was changedto 0.2 percent by weight.

In said knitted fabric, sweat absorbability: 56 mm, bulkiness: 2.20cm³/g, flexural rigidity: 0.018 cN·cm²/cm, hand: 5 grade, over-allevaluation: 3 grade.

Comparative Example 1

A knitted fabric was obtained similarly to Example 1, except that thecross section shape of the filament was changed to a circular crosssection.

In said knitted fabric, sweat absorbability: 25 mm, bulkiness: 2.08cm³/g, flexural rigidity: 0.024 cN·cm²/cm, hand: 2 grade, over-allevaluation: 1 grade.

Comparative Example 2

A knitted fabric was obtained similarly to Example 1, except that theknitted fabric having the same half knit construction as in Example 1was made by feeding all of the multifilament yarns used in ComparativeExample 1 into the back reed and alternately feeding four of themultifilament yarns used in Comparative Example 1 and one of the flatmultifilament yarns used in Example 1 into the front reed, so that thecontent of the flat multifilament yarns used in Example 1 and thecontent of the multifilament yarns used in Comparative Example 1 were 10percent by weight and 90 percent by weight, respectively.

In said knitted fabric, sweat absorbability: 28 mm, bulkiness: 2.10cm³/g, flexural rigidity: 0.022 cN·cm²/cm, hand: 3 grade, over-allevaluation: 2 grade.

Industrial Applicability

The flat multifilament yarn knitted fabric of the present invention hasexcellent bulkiness and drape, because the single filaments well slipdue to their special cross section shapes and further because the yarnsare flattened and spread in the lateral direction at the connectionpoints of the knitted fabric construction with contact pressures to formthe loops of the knitted fabric, and further has excellent waterabsorbability and sweat absorbability. Thereby, the flat multifilamentyarn knitted fabric of the present invention is useful as a knittedfabric for inner wears such as underwear and as a sports wear.

1. A flat multifilament yarn knitted fabric comprising multifilamentyarns each comprising a plurality of flat cross section shape-havingfilaments comprising a fiber-forming thermoplastic polymer as a maincomponent, characterized in that three or more expanded portionsexpanded toward the outside of the longitudinal central line of the flatcross section of the above-described filament per half side of the flatcross section and two or more constricted portions formed between theexpanded portions per half side are formed on both the sides of thelongitudinal central line, approximately symmetrically with respect tothe above-described longitudinal central line, in the flat cross sectionof the filament; cross section flatness represented by the ratio (B/C1)of the length (B) of the above-described modified cross section in thedirection of the longitudinal central line to the maximum width (C1) inthe direction orthogonal to the direction of the longitudinal centralline is in a range of 2 to 6; and the above-described multifilamentyarns are comprised in the knitted fabric in an amount of 50 to 100percent by weight based on the total weight of the knitted fabricwherein a K value determined by the following expression is not morethan 35×10³, as the whole of the above-described knitted fabric,K=Co×We×(D/1.1)^(1/2) wherein Co is the course number (courses/2.54 cm)of the knitted fabric; We is the wale number (wales/2.54 cm) of theknitted fabric; and D is the average value (dtex) of the totalfinenesses of the yarns constituting the knitted fabric.
 2. The flatmultifilament yarn knitted fabric according to claim 1, wherein theabove-described fiber-forming thermoplastic polymer is selected frompolyesters, polyamides, polyvinylidene chloride, and polypropylene. 3.The flat multifilament yarn knitted fabric according to claim 1, whereinthe ratio (C1/C2) of the maximum value (C1) of the width to the minimumvalue (C2) in the flat cross section of the above-described filament is1.05 to 4.00.
 4. The flat multifilament yarn knitted fabric according toclaim 1, wherein the above-described filament yarn contains a mattingagent in an amount of not less than 0.2 percent by weight.
 5. The flatmultifilament yarn knitted fabric according to claim 1, wherein thetotal fineness of the above-described multifilament yarn is 20 to 170dtex, and the fineness of the single filament is 0.5 to 5 dtex.
 6. Theflat multifilament yarn knitted fabric according to claim 1, wherein theabove-described knitted fabric has a knit construction selected fromponti roma, Milano rib, tuck rib, back seed stitch (back Kanoko), singlepique, double pique, half, satin, back half, queens cord, shark skin,double raschel, and double tricot.
 7. The flat multifilament yarnknitted fabric according to claim 1, wherein the bulkiness of theabove-described knitted fabric, measured by JIS L 1018-1998,
 6. 20, isnot less than 2.1 cm³/g.
 8. The flat multifilament yarn knitted fabricaccording to claim 1, wherein the flexural rigidity of theabove-described knitted fabric, measured with a KES hand-measuringsystem, is not more than 0.02 cN□cm²/cm.
 9. The flat multifilament yarnknitted fabric according to claim 1, wherein the water-absorbing speedof the above-described knitted fabric, measured by JIS L 1096:1998, 6.26, 1(2) B method (Byreck method), is not less than 30 mm.